Functionalization of silicon nanowire arrays by silver nanoparticles for the laser desorption ionization mass spectrometry analysis of vegetable oils

Abstract

In this work, novel hybrid nanostructured surfaces, consisting of dense arrays of silicon nanowires (SiNWs) functionalized by Ag nanoparticles (AgNP/SiNWs), were used for the laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) analysis of some typical unsaturated food components (e.g. squalene, oleic acid) to assess their MS performance. The synthesis of the novel platforms is an easy, cost-effective process based on the maskless wet-etching preparation at room temperature of SiNWs followed by their decoration with AgNPs, produced by pulsed laser deposition. No particular surface pretreatment or addition of organic matrixes/ionizers was necessary. Moreover, oil extracts (e.g. extra virgin olive oil, peanut oil) could be investigated on AgNP/SiNWs surfaces, revealing their different MS profiles. It was shown that such substrates operate at reduced laser energy, typically generating intense silver cluster ions and analyte adducts. A comparison with bare SiNWs was also performed, indicating the importance of AgNP density on NW surface. In this case, desorption/ionization on silicon was invoked as probable LDI mechanism. Finally, the influence of SiNW length and surface composition on MS results was assessed. The combination of typical properties of SiNWs (hydrophobicity, antireflectivity) with ionization ability of metal NPs can be a valid methodology for the further development of nanostructured surfaces in LDI-TOF MS applications. Copyright © 2016 John Wiley & Sons, Ltd.

Gold Nanoparticles Synthesis Using Stainless Steel as Solid Reductant: A Critical Overview

“…Histograms were produced on three replicates, counting more than 800 nanoparticles. X-ray photoelectron spectroscopy measurements were performed on both steel rods and gold colloids deposited on silicon substrates, using a PHI Versaprobe II (Chanhassen, MN, USA) spectrometer equipped with monochromatized Al-Kα radiation (1486.6 eV), following a previously reported procedure [34,35]. Binding energy (BE) scale was corrected on C1s component at 284.8 eV.…”

Mechanisms of Nanophase-Induced Desorption in LDI-MS. A Short Review

“…However, this classification is somewhat limiting since, for instance, pure carbon can behave as an insulator, a semiconductor or a metal depending on its structure or atomic arrangement. Further, recently explored hybrid systems such as gold nanoparticles (AuNPs) supported on silicon plate with cationic copolymer [34], iron oxide nanoparticles modified with sinapic acid [35] or magnetic NPs coupled to TiO 2 [36], SiNWs functionalized by Ag nanoparticles [37,38], would not be included as well. Lately, Yonezawa et al [39] divided SALDI-MS techniques into two categories: (i) nanostructured surfaces such as commercially available DIOS, NALDI, Quickmass, and (ii) nanoparticle systems including diverse inorganic nanoparticles or combination of them.…”

“…Concerning the first topic, besides the papers already cited, great effort is devoted to fabricate hybrid systems such as α-cyano-4-hydroxycinnamic acid-modified AuNPs [40], immobilized silica and 2,5-dihydroxybenzoic acid on iron oxide magnetic nanoparticles [41], or combination of metal nanoparticles and semiconductor materials [37,38]. It is worth noting the general tendency to move from macroscopically flat surfaces to nanostructured materials, due to several potential benefits, including: an extended dynamic range (due to an increased surface area and analyte loading capacity); improved reproducibility (due to intimate analyte incorporation and deposition homogeneity); superior sensitivity and energy-transfer efficiency (due to the unique optical and thermal properties of nanomaterials).…”

Catalytic Activity of Silicon Nanowires Decorated with Gold and Copper Nanoparticles Deposited by Pulsed Laser Ablation

“…Silicon nanowires (SiNWs) are attracting worldwide research interest due to their fascinating properties and application in a wide range of areas, such as electronics, photovoltaics, solar cells, diagnostics, molecular sensing, batteries, catalysis, and analytical chemistry [1,2,3,4,5,6,7]. …”